Double row compressor stators

ABSTRACT

A method of manufacturing a compressor stator having: a first stator blade with a first leading edge and a first trailing edge; a second stator blade disposed a circumferential distance from the first stator blade, the second stator blade having a second leading edge disposed an axial distance from the first leading edge and a second trailing edge disposed an axial distance from the first trailing edge; the method comprising: using additive manufacturing to deposit and fuse together progressive layers of metal material commencing at a substrate to form the first stator blade, the second stator blade, at least one intermediate support structure disposed between the first stator blade and the second stator blade, and at least one primary support structure disposed between the substrate and at least one of: the first stator blade; and the second stator blade; and removing the primary support structure and the intermediate support structure.

TECHNICAL FIELD

The disclosure relates generally to gas turbine engines, and moreparticularly to a method of manufacturing a double row compressor statorhaving overlapping or interlaced pairs of stator blades.

BACKGROUND

Overlapping, interlaced or tandem pairs of compressor stator blades aredescribed in U.S. Pat. No. 9,951,635 to Guemmer, U.S. Pat. No. 8,573,941to Hoeger and U.S. Pat. No. 9,957,806 to Johann et al.

To manufacture such pairs of blades, the prior art suggests that eachblade is manufactured separately and then the pairs are assembledtogether by brazing or welding of the metal components.

Improvement is desirable particularly in view of current metalfabrication techniques.

SUMMARY

In one aspect, the disclosure describes a method of manufacturing acompressor stator having an axis and a circumference, the compressorstator having: a first stator blade with a first leading edge and afirst trailing edge; a second stator blade disposed a circumferentialdistance from the first stator blade, the second stator blade having asecond leading edge disposed an axial distance from the first leadingedge and a second trailing edge disposed an axial distance from thefirst trailing edge; the method comprising: using additive manufacturingto deposit and fuse together progressive layers of metal materialcommencing at a substrate to form the first stator blade, the secondstator blade, at least one intermediate support structure disposedbetween the first stator blade and the second stator blade, and at leastone primary support structure disposed between the substrate and atleast one of: the first stator blade; and the second stator blade; andremoving the at least one primary support structure and the at least oneintermediate support structure.

In another aspect, the disclosure describes a precursor fabrication foradditive manufacturing of a compressor stator, the compressor statorhaving an axis and a circumference, the precursor fabrication having: afirst stator blade with a first leading edge and a first trailing edge;a second stator blade disposed a circumferential distance from the firststator blade, the second stator blade having a second leading edgedisposed an axial distance from the first leading edge and a secondtrailing edge disposed an axial distance from the first trailing edge; asubstrate; at least one primary support structure disposed between thesubstrate and at least one of: the first stator blade; and the secondstator blade; and at least one intermediate support structure disposedbetween the first stator blade and the second stator blade.

Further details of these and other aspects of the subject matter of thisapplication will be apparent from the detailed description includedbelow and the drawings.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, in which:

FIG. 1 shows an axial cross-section view of a prior art turbo-fan gasturbine engine;

FIG. 2 shows an axial radially outward sectional view of overlappingpairs of upstream and downstream stator blades in accordance with thepresent description.

FIG. 3 is a radial sectional view along line 3-3 of FIG. 2.

FIG. 4 is an elevation view of an additive manufactured precursorfabrication showing an overlapping pair of upstream and downstreamstator blades with primary supports extending from the base substrate onwhich progressive layers are deposited and intermediate supports betweenthe stator blades, in accordance with the present description

DETAILED DESCRIPTION

FIG. 1 illustrates a gas turbine engine comprising in serial flowcommunication a fan 1 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16 inwhich the compressed air is mixed with fuel and ignited for generatingan annular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases.

Within the multistage compressor 14 there are multiple stages comprisingrotor blades 1, stator blades 2 and guide vanes 3 that are arranged inrings of blades 1, 2, 3 in a circumferential array about a common engineaxis 4. The rotor blades 1 and stator blades 2 usually include axiallyextending platforms (not shown in FIG. 1) to define the radial and axialsurfaces of the gas flow path through the multistage compressor 14. Theplatforms and blades 1, 2 are generally manufactured together in a unit,i.e.: one blade per platform, using reductive machining from a solidmetal blank or by metal casting. Each stator blade 2 with platform thatis radially inward of the platform, is secured into a stator ring toform a multiple stator blade assembly. Further description in notconsidered necessary since the manufacture and assembly of rotors andstators for the compressors of gas turbine engines is within the commongeneral knowledge of those skilled in the relevant technologies.

FIGS. 2-3 show an example embodiment wherein a pair of stator blades (afirst stator blade 5 and a second stator blade 6) are joined to aradially inner platform 7 and a radially outer platform 8. The firststator blade 5 has a first leading edge 9 and a first trailing edge 11.The second stator blade 6 is disposed a circumferential distance fromthe first stator blade 5. The second stator blade 6 has a second leadingedge 13 disposed an axial distance from the first leading edge 9 and asecond trailing edge 15 disposed an axial distance from the firsttrailing edge 11.

The example illustrated shows the first stator blade 5 and second statorblade 6 being the same size and shape. Depending on the gas flowrequirements, it will be understood that any arrangement orconfiguration of tandem/overlapping/interleaved blades 5, 6 may be used.For example blade 6 may be larger or smaller than blade 5, blade 6 canhave a different surface configuration or is axially forward rather thanaft of blade 5.

Referring to FIG. 3 the inner platform 7 spans between a radially innerend 17 of the first stator blade 5 and an inner end 19 of the secondstator blade 6. The outer platform 8 likewise spans between a radiallyouter end 20 of the first stator blade 5 and an outer end 21 of thesecond stator blade 6. A transition fillet between the ends (17, 19, 20,21) of the blades (5, 6) and the adjacent surfaces of the platforms (7,8) is desirable to define the gas path.

FIG. 3 shows a removal access window 22 disposed in both the innerplatform 7 and in the outer platform 8, the function of which isdescribed below. The rotor may include only an inner platform 7 or onlyan outer platform 8 and accordingly a removal access window 22 would insuch a case be provided in only one platform 7, 8.

Reference is made to FIG. 4 which shows an example of how the additivemanufacturing of tandem/overlapping/interleaved blades 5, 6 and attachedplatforms 7, 8 may be accomplished. Additive manufacturing uses metalparticles to deposit and fuse together progressive layers of metalmaterial commencing at a substrate 23 and progressing upwardly asindicated by arrow 24. Progressive layers form the first stator blade 5,the second stator blade 6, at least one intermediate support structure25 disposed between the first stator blade 5 and the second stator blade6, and at least one primary support structure 26 disposed between thesubstrate 23 and at least one of: the first stator blade 5; and thesecond stator blade 6.

In the example illustrated, the primary support structure 26 does notextend to the first stator blade 5 nor to the outer platform 8. Ifrequired the primary support structure 26, made of thin posts depositedin layers together with the blades 5, 6 and platform 8, can extendupwards. However current additive manufacturing processes allow forlayers to be deposited to form an angle relative to the substrate 23that is in the range between 45 degrees and 90 degrees (i.e.: vertical).Accordingly as illustrated the additive manufacturing process does notrequire supports 25, 26 to deposit material where the angle “a” relativeto the substrate is 45 degrees or more.

After the blades 5, 6 and platforms 7, 8 with supports 25, 26 are fullydeposited, the supports 25, 26 are removed. The removal access window 22provides access to the supports 26, 27 and to the gas path surfaces ofthe blades 5, 6 and platforms 7, 8, the at least one primary supportstructure and the at least one intermediate support structure.

By inserting a machining tool through the removal access window 22 thetool can remove at least one of: the at least one primary supportstructure 26; and the at least one intermediate support structure 25.After removal a closure piece 27 that matches the size of the removalaccess window 22 and continues the contours of the platform 8 is fittedand secured within the removal access window 22 by brazing or weldingfor example. Before securing the closure piece 27, manufacturing caninclude inserting a finishing tool through the removal access window 22to remove excess surface material from at least one of: first statorblade 5; the second stator blade 6; the inner platform 7; and the outerplatform 8 with the finishing tool.

For further clarity, it will be understood that FIG. 4 shows a precursorfabrication 28 for additive manufacturing of a compressor stator, thecompressor stator having an axis 4 (FIGS. 1 and 2) and a circumference.The precursor fabrication 28 includes: a first stator blade 5 and asecond stator blade 6 disposed a circumferential distance from the firststator blade 5. The second stator blade 6 has a second leading edge 13disposed an axial distance from the first leading edge 9 and a secondtrailing edge 15 disposed an axial distance from the first trailing edge11. Additive manufacturing commences by depositing layers of metalmaterial on the substrate 23 and includes forming of at least oneprimary support structure 26 disposed between the substrate 23 and atleast one of: the first stator blade 5; and the second stator blade 6;and at least one intermediate support structure 25 disposed between thefirst stator blade 5 and the second stator blade 6. As shown in FIG. 4,the platforms 7, 8 can be formed with the removal access window 22 atthe same time as the closure piece 27 is formed on the substrate 23.

The above description is meant to be exemplary only, and one skilled inthe relevant arts will recognize that changes may be made to theembodiments described without departing from the scope of the inventiondisclosed. The present disclosure may be embodied in other specificforms without departing from the subject matter of the claims. Thepresent disclosure is intended to cover and embrace all suitable changesin technology. Modifications which fall within the scope of the presentinvention will be apparent to those skilled in the art, in light of areview of this disclosure, and such modifications are intended to fallwithin the appended claims. Also, the scope of the claims should not belimited by the preferred embodiments set forth in the examples, butshould be given the broadest interpretation consistent with thedescription as a whole.

1. A method of manufacturing a compressor stator having an axis and acircumference, the compressor stator having: a first stator blade with afirst leading edge and a first trailing edge; a second stator bladedisposed a circumferential distance from the first stator blade, thesecond stator blade having a second leading edge disposed an axialdistance from the first leading edge and a second trailing edge disposedan axial distance from the first trailing edge; the method comprising:using additive manufacturing to deposit and fuse together progressivelayers of metal material commencing at a substrate to form the firststator blade, the second stator blade, at least one intermediate supportstructure disposed between the first stator blade and the second statorblade, and at least one primary support structure disposed between thesubstrate and at least one of: the first stator blade; and the secondstator blade; and removing the at least one primary support structureand the at least one intermediate support structure.
 2. The methodaccording to claim 1, wherein the compressor stator includes: an innerplatform spanning between an inner end of the first stator blade and aninner end of the second stator blade; and an outer platform spanningbetween an outer end of the first stator blade and an outer end of thesecond stator blade; and a removal access window disposed in at leastone of: the inner platform; and the outer platform; and the methodincluding: inserting a machining tool through the removal access windowto remove at least one of: the at least one primary support structure;and the at least one intermediate support structure, with the machiningtool; and securing a closure piece within the removal access window. 3.The method according to claim 2, wherein the method includes, beforesecuring the closure piece, inserting a finishing tool through theremoval access window to remove excess surface material from at leastone of: the first stator blade; the second stator blade; the innerplatform; and the outer platform. 4.-6. (canceled)